A Novel End-to-End Simulation Framework for Internal Flow in pMDIs: Coupled Modeling of Cavitation, Flash Boiling,...

Area of Science:

• Fluid dynamics
• Aerosol science
• Computational modeling

Background:

• Pressurized metered dose inhalers (pMDIs) are widely used but often perform suboptimally.
• Existing models lack comprehensiveness, hindering understanding of pMDI inefficiencies from propellant injection to plume formation.

Purpose of the Study:

• To develop and validate a novel multiphase computational framework for simulating internal pMDI flow phenomena.
• To accurately predict aerosol plume characteristics and dynamics.

Main Methods:

• Utilized a volume of fluid (VOF) approach for multiphase flow simulation.
• Captured key phenomena: cavitation, flash boiling, and atomization.
• Validated the model using high-speed imaging and X-ray imaging data.

Main Results:

• The model accurately reproduced experimental plume characteristics, including mass median diameter (2.7 μm vs. 3 μm).
• Predicted initial spray velocity (~110 m/s) and cone angle (~21°) aligned well with high-speed imaging data.
• Demonstrated predictive capability against multiple experimental datasets.

Conclusions:

• The developed VOF framework offers a powerful tool for understanding and optimizing pMDI performance.
• Enables formulation-specific optimization of inhaler design for various therapeutic applications.
• Advances the development of tailored pMDIs by moving beyond generic approaches.